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3 BACKGROUND k'■ KLEINFELDER Tradeway Chevrolet is an operating automobile dealership in Manteca, California (Plate 1). Tradeway Chevrolet operates a automobile service shop on the site with associated hydraulic vehicle lifts. A soil and groundwater investigation was undertaken by Advanced GeoEnvironmental, Inc. (AGE) in July 1999 for Union Safe Bank. The results of the investigation are detailed in a report entitled "Preliminary Site Investigation Report, Tradeway Chevrolet" dated July 14, 1999. In that investigation AGE advanced a total of 17 soil probes and collected a total of 3 grab groundwater samples from selected probe locations for laboratory analysis. Only TPH-g, TPH-d, and TPH-mo was detected in the soil samples in probe location P-6 located near one of the hydraulic lifts within the service area. The detected concentrations of TPH-g, TPH-d, and TPH-mo were 1.4 mg/kg, 13,000 mg/kg, and 16,000 mg/kg respectively. The grab groundwater sample analyzed from probe location P-6 showed concentrations of TPH-d and TPH-mo with concentrations of 2,300 ug/L and 3,300 ug/L respectively. The AGE report had the following conclusions and recommendations: On the basis of the information reviewed and collected during this investigation, AGE concludes: • Petroleum hydrocarbon compounds were detected in 1 of the 19 soil samples analyzed (Table 1) The reported detections of petroleum hydrocarbon compounds were in a soil sample colleted from soil probe boring P-6 located adjacent to a hydraulic lift within the dealership service department. TPH-g, TPH-d, and TPH-mo were detected in the soil sample collected at 10.5 feet bgs at concentrations of 1.4 mg/kg, 13,000 mg/kg, and 16,000 mg/kg, respectively. Laboratory analytical results indicate that a release of petroleum hydrocarbons has apparently occurred from the hydraulic lift located adjacent to probe P-6. There were no reported detections of BTEX, TPH-g, TPH-d, TPH-mo, MTBE, or PCBs in any of the soil samples collected from the additional hydraulic lift locations, former gasoline and waste oil UST locations or areas of surficial staining. Based on the laboratory analytical results, no releases of petroleum hydrocarbons were detected from the additional hydraulic lift locations, former gasoline and waste oil UST locations, or areas of surficial staining. • Concentrations of TPH-d and TPH-mo were detected in one of the three ground water samples analyzed (Table 2). TPH-d and TPH-mo were detected in the ground water sample collected from probe boring P-6 at 2,300 ug/1 and 3,300 ug/l, respectively. Analytical results indicate that a release of petroleum hydrocarbon compounds has apparently occurred from the hydraulic lift located adjacent to probe P-6 and has impacted ground water. The reported concentration of TPH- d exceeded the U.S. Environmental Protection Agency -suggested or established contaminant level for TPH-mo in ground water. Based on the laboratory analytical results, no releases of petroleum hydrocarbons were detected at the other hydraulic lift locations or the former location of the gasoline UST. Based on data reviewed and collected at the site, AGE recommends: 20-3978-03.CHEV / ST02k111 Page 5 of 18 Copyright 2002, Kleinfelder, Inc. July 1, 2002